Users of portable devices have a desire for optical devices that exhibit a high resolution and a small size and have various photographing functions (e.g., optical zoom-in/zoom-out, auto-focusing (AF), and handshaking correction or optical image stabilization (OIS) functions). Although these photographing functions may be implemented by combining several lenses and directly moving the lenses, the size of an optical device may be increased when the number of lenses is increased.
Auto-focusing and handshaking correction functions are implemented by moving or tilting several lens modules, which are fixed to a lens holder and aligned with the optical axis, along the optical axis or in the direction perpendicular to the optical axis, and a separate lens-driving device is used to drive the lens modules. However, the lens-driving device exhibits high power consumption, and a glass cover needs to be separately added to a camera module in order to protect the lens-driving device, thus causing an increase in the overall thickness.
Therefore, studies have been conducted on a liquid lens, which performs auto-focusing and handshaking correction functions by electrically adjusting the curvature of an interface of two types of liquids.